Masakazu Ono

NB-FACE: No-Beacon FACE Ad-hoc Routing Protocol for Reduction of Location Acquisition Overhead

For development of ad-hoc networks and sensor networks where wireless multihop message transmission among multiple mobile computers, design and implementation of routing protocols with lower communication overhead are critical. Here, characteristics and performance of a routing protocol primarily depend on the method for transmission of Rreq to a destination mobile computer. Many ad-hoc routing protocols apply flooding of an Rreq message. FACE routing protocol transmits an Rreq message without flooding. Though each mobile computer receiving an Rreq message determines its next hop mobile computer only by location of neighbor mobile computers, it surely detects a message transmission route; i.e. no deadend. However, it is required for each mobile computer to exchange its location repeatedly since up-to-date location of all neighbor mobile computers is used for determination of a next hop mobile computer. This paper proposes a novel ad-hoc routing protocol NB-FACE (No Beacon FACE) routing protocol which determines a next hop mobile computer without location of neighbor mobile computers and achieves the same message transmission route as FACE.

Wireless sporadic communication protocol for supporting cluster-to-base station communication

Recently, mobile computers have become able to communicate with each other by using a wireless LAN protocol, e.g. IEEE 802.11 and HIPERLAN, for supporting various Internet services. In the case when a mobile computer changes location with high speed, less messages are exchanged between the mobile computer and the Internet. This paper proposes a novel routing protocol CB-WSCP for mobile clustered networks in which mobile computers with almost the same velocity and communication with each other by multi-hop transmission form a cluster. Here, communication between a cluster and a base station is available only if a mobile computer in the cluster is within transmission range of the base station. Hence, it is required to support sporadic communication. For achieving wider bandwidth even though the cluster moves with high speed, the proposed protocol achieves switching of gateways and updating of routing tables.

Stable storage for wireless multi-hop access networks

This paper has proposed a method to realize k-resilient distributed stable storage in a checkpoint protocol for a wireless multi-hop access network. By using the method, state information of a mobile computer is stored into storage devices in neighbor mobile computers and less state information is stored into a stable storage in a base station. Hence, communication and storage overhead are reduced. The method is able to be applied to a 3-phase checkpoint protocol without any additional messages. For further reduction of the overhead, not only 1-hop neighbor but also 2-hop neighbor mobile computers are involved into achieving the distributed stable storages. We design a checkpoint protocol by using the proposed method. In simulation evaluation, only 10-20% storage overhead of a naive method storing all state information into a stable storage in a base station is required. Especially in case of sparser mobile computer distribution and higher failure ratio, our extension involving 2-hop neighbor mobile computers works efficiently for reduction of the overhead

Hybrid checkpoint protocol for cell-dependent infrastructured networks

For supporting mission-critical applications in a mobile network system, hybrid checkpointing has been proposed. In a recent mobile network, wireless LAN protocols such as IEEE 802.11 and HlPERLAN are getting popular and communication with mobile computers is realized by using mobile IP in the Internet. This paper proposes a novel hybrid checkpoint protocol. Here, message logging for mobile computers is achieved based on broadcast property of wireless LAN protocols. In addition, by extending mobile IP, network overload in recovery is avoided. For both check- pointing and recovery in the proposed protocol, all required information is piggied back to messages. That is, no additional message is required.

Communication-induced multimedia checkpoint protocol

For achieving an environment for mission-critical network applications with multimedia message transmission, the authors have proposed a novel global consistency for a set of local checkpoints. It reflects features of multimedia network applications. Based on the consistency, the authors have designed a centralized synchronous checkpoint protocol. In order to reduce communication overhead for checkpointing and recovery, This work proposes a communication-induced checkpoint-recovery protocol.